linux-stable/include/linux/virtio_balloon.h
Adam Litke 9564e138b1 virtio: Add memory statistics reporting to the balloon driver (V4)
Changes since V3:
 - Do not do endian conversions as they will be done in the host
 - Report stats that reference a quantity of memory in bytes
 - Minor coding style updates

Changes since V2:
 - Increase stat field size to 64 bits
 - Report all sizes in kb (not pages)
 - Drop anon_pages stat and fix endianness conversion

Changes since V1:
 - Use a virtqueue instead of the device config space

When using ballooning to manage overcommitted memory on a host, a system for
guests to communicate their memory usage to the host can provide information
that will minimize the impact of ballooning on the guests.  The current method
employs a daemon running in each guest that communicates memory statistics to a
host daemon at a specified time interval.  The host daemon aggregates this
information and inflates and/or deflates balloons according to the level of
host memory pressure.  This approach is effective but overly complex since a
daemon must be installed inside each guest and coordinated to communicate with
the host.  A simpler approach is to collect memory statistics in the virtio
balloon driver and communicate them directly to the hypervisor.

This patch enables the guest-side support by adding stats collection and
reporting to the virtio balloon driver.

Signed-off-by: Adam Litke <agl@us.ibm.com>
Cc: Anthony Liguori <anthony@codemonkey.ws>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (minor fixes)
2010-02-24 14:22:08 +10:30

36 lines
1.2 KiB
C

#ifndef _LINUX_VIRTIO_BALLOON_H
#define _LINUX_VIRTIO_BALLOON_H
/* This header is BSD licensed so anyone can use the definitions to implement
* compatible drivers/servers. */
#include <linux/virtio_ids.h>
#include <linux/virtio_config.h>
/* The feature bitmap for virtio balloon */
#define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */
#define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
struct virtio_balloon_config
{
/* Number of pages host wants Guest to give up. */
__le32 num_pages;
/* Number of pages we've actually got in balloon. */
__le32 actual;
};
#define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */
#define VIRTIO_BALLOON_S_SWAP_OUT 1 /* Amount of memory swapped out */
#define VIRTIO_BALLOON_S_MAJFLT 2 /* Number of major faults */
#define VIRTIO_BALLOON_S_MINFLT 3 /* Number of minor faults */
#define VIRTIO_BALLOON_S_MEMFREE 4 /* Total amount of free memory */
#define VIRTIO_BALLOON_S_MEMTOT 5 /* Total amount of memory */
#define VIRTIO_BALLOON_S_NR 6
struct virtio_balloon_stat {
u16 tag;
u64 val;
} __attribute__((packed));
#endif /* _LINUX_VIRTIO_BALLOON_H */